1) Field of the Invention
The field of the present invention generally relates to control networks and related methods for configuring and operating control networks.
2) Background
Automated control systems are commonly used in a number of manufacturing, transportation, and other applications, and are particularly useful for controlling machinery, sensors, electronics, and other system components. For example, manufacturing or vehicular systems may be outfitted with a variety of sensors and automated electrical and/or mechanical parts that require enablement or activation when needed to perform their assigned functions. Such systems commonly require that functions or procedures be carried out in a prescribed order or with a level of responsiveness that precludes sole reliance on manual control. Also, such systems may employ sensors or other components that require continuous or periodic monitoring and therefore lend themselves to automated control.
As the tasks performed by machinery and electronics have grown in number and complexity, a need has arisen for ways to exercise control over the various components of a system rapidly, efficiently and reliably. The sheer number of system components to be monitored, enable, disabled, activated, deactivated, adjusted, or otherwise controlled can lead to challenges in designing and implementing sophisticated control systems. As the number of controlled components in a system increases, not only do control functions become more complicated, but also the writing of inter-connections of the control system become more elaborate and complex. A robust, scalable control system is therefore needed.
In addition, increasing reliance on automated control in various fields has resulted in more significant potential consequences if the automated control system fails. Therefore, a need exists for a reliable control system that is nevertheless capable of controlling large systems if necessary.
Traditionally, control systems in certain applications, such as transit vehicles and railcars, have relied upon relay-based control technology. In such systems, relays and switches are slaved to a logic circuit that serves to switch signal connections. This approach requires a large number of relays and a substantial amount of wiring throughout the vehicle. In some instances distributed processors or logic circuits may be used for subsystems such as the door, but these processors or logic circuits often take up significant space and can be costly to maintain.
Substantial improvements in the field of automated control in general, and vehicular control in particular. Various such improvements are described, for example, in U.S. Pat. Nos. 5,907,486, 6,061,600, 6,094,416, 6,147,967, and 6,201,995, all of which are assigned to the assignee of the present invention, and all of which are hereby incorporated by reference as if set forth fully herein.
In recent years, increasing attention has been given to fiber optic networks. Many fiber optic networks are used solely or primarily to transport data. Some fiber optic networks have a ring architecture, wherein data is transmitted from an originating node to a destination node by passing through each intervening node in the ring. To provide some measure of redundancy and increased reliability, in the case of, e.g., a fiber optic break in the ring, a two fiber ring network has been developed, with one ring designated as the working ring (or service ring) and the other ring designated as the protection ring. Data is ordinarily transported over the working ring. However, if a break or other failure occurs in the working ring, data is looped back on the protection ring at the nodes adjacent to the failure, thereby effectively forming a new loop.
In order to increase throughput and/or reliability even further, some network architectures have been proposed with four fiber rings, two of which are working rings and two of which are protection rings. Also, various schemes have been proposed for selecting different wavelengths on the fibers to achieve higher data throughput or increased flexibility.
While the variety of fiber optic networks continues to proliferate, relatively little advancement has been made in applying fiber optic networks to control system applications. Few, if any, fiber optic network architectures and protocols provide an optimal combination of reliability, simplicity, versatility, scalability, and robustness suitable for control system applications.
Accordingly, it would be advantageous to provide a fiber optic control system, architecture, and method that overcomes one or more of the foregoing problems, disadvantages, or drawbacks.